连续解吸中离子强度对可变电荷土壤和高岭石体系pH的影响  

Effect of Ionic-strength Change on the System pH of Variable Charge Soils and Kaolinite during Successive Desorption

作　　者：罗文贱[1] 张政勤[1] 陈勇[1] 邹献中[1] 

机构地区：[1]广东省农业科学院农业资源与环境研究所农业部南方植物营养与肥料重点实验室广东省养分资源循环利用与耕地保育重点实验室,广州510640

出　　处：《土壤学报》2016年第1期146-154,共9页Acta Pedologica Sinica

基　　金：广东省自然科学基金项目(2015A030313567);广东省中小企业发展资金项目资助~~

摘　　要：研究了两种可变电荷土壤中在去离子水中和0.1 mol L-1 Na NO3溶液中吸附铜离子和钙离子后依次被浓度从低到高的Na NO3溶液连续解吸时,离子强度变化对每次解吸前后体系p H变化(Δp H)的影响,为了进一步了解其相关机理,作为对照,也研究了各种条件下,离子强度变化对高岭石Δp H的影响。结果表明,无论是否有吸附性二价阳离子的存在,或者吸附性阳离子属性(专性吸附型离子或电性吸附型离子)如何,当样品依次被去离子水、0.01 mol L-1 Na NO3、0.1 mol L-1 Na NO3以及1 mol L-1 Na NO3解吸时,在去离子水中和Na NO3溶液中的解吸过程对Δp H的影响截然不同。总体而言,如果解吸时体系离子强度趋于降低,Δp H将为正值,反之则为负值,且Δp H变幅开始增大时的起始点所对应的p H吸附基本相同,该起始点应该与高岭石ZPC(电荷零点)紧密相关。对上述结果的分析表明,解吸过程中,引起上述Δp H变化规律的根本原因之一是连续解吸过程中的离子强度变化导致的可变电荷表面的表面电位变化。To investigate effect of change of ion-strength on change of p H（Δp H）during successively desorption,a serious desorption tests were conducted on using electrolyte solutions,including de-ionized water,varied in Na NO3 concentration from low to high,to desorbed successively copper ions or calcium ions adsorbed by two variable charge soils（Ali-Haplic Acrisol from Jinxian of Jiangxi and Hyper-Rhodic Ferralsol from Kunming of Yunnan）. To explore relative mechanism further,kaolinite is also be used,and the similar experience processes have also been conducted without the addition of bivalent adsorbing cations. Results showed that de-ionized water and Na NO3 electrolyte solutions differed in effect on Δp H,when samples were successively desorbed in de-ionized water,0.01 mol L-1 Na NO3,0.1 mol L-1 Na NO3,1 mol L-1Na NO3,respectively,no matter if the addition of bivalent adsorbing cations,or the type of cations adsorbed（specific adsorption ions or electrolyte adsorption ions）. Although the value of Δp H is different in different condition of desorption and different samples,the tendency of change of Δp H is just the same. In general,Δp H was always positive,when the samples were desorbed in de-ionized water,and was generally negative when desorbed in Na NO3. Δp H will decrease with the increasing times of desorption in de-ionized water,and will be maintain not change or slight increase when desorbed in the same concentration of Na NO3 solution for the second or the third times. There is seemly the similar point of beginning of p Had（p H of equilibrium suspension of adsorption）for the variable charge soils and kaolinite,which is relative to the ZPC（Zero Point of Charge）of kaolinite,when desorption occurred in de-ionized water and 0.01 mol L-1 Na NO3 for the first time. The tendency of change of value of Δp H of which supporting electrolyte is 0.1 mol L-1 Na NO3,is sharper than that supporting electrolyte is de-ionized water,when p Had is above the special point,no matter the desorption was occur

关 键 词：可变电荷土壤 高岭石 连续性解吸 离子强度 pH变化特征 

分 类 号：S153.3[农业科学—土壤学]